Telephone system



June24, 1930. R. F. STEHLIK TELEPHONE SYSTEM 4 Sheets-Sheet Originai Filed July 6. 1925 'EuduLnh F." 51551 June 24, 1930.

R. F. STEHLIK TELEPHONE SYSTEM Original Filed July 6. 1926 4 Sheets-Sheet 2 Efidglph F. gi -H111;

' June 24, 1930. R. F. sT EHLlK TELEPHONE SYSTEM Original Filed July 6. 1925 4 Sheefgs-Shgt a -II H June 24, 1930..' R. F STEHLIK 5 TELEPHONE SYSTEM Original Filed July 6. 1926 4 Sheets-Sheet 4 Patented June 24, 1930 UNITED STATES PATET ,,FFICE RUDOLPH F. STEHLIK, OF CHICAGO, ILLINOIS, ASSIGNOR. T AUTOMATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE TELEPHONE I SYSTEM Application filed July 6, 1926, Serial No. 120,547. Renewed February 3, 1930.

This invention relates in general to tele phone systems but is concerned particularly With such systems in which line finders are employed to connect an idle trunk line with a calling line; and the principal object of the invention briefly stated, is the production of a new and improved finder switch system, which is so designed as to permit cheapness in manufacture and maintenance without impairing the reliability and efficiency of the system.

Finder switch systems which have been devised heretofore employ one or more relays individual to each line in the system, r5- those relays being operated, when that line makes a call, to start a finder in operation to connect with that line. In addition to the relays individual to the lines such systems have employed a certain amount of control equipment common to a group of lines, through which equipment the actual setting of the various finders of the system is exercised. The combination of individual line relays and common control equipment for a group of lines, makes the initial cost of the system and the expense of mainte-' nance, so high .as to be objectionable. A relay is not an expensive device, however an individual relay for every line in anexchange runs into considerable money, as obviously there would be ten thousand of such relays in a ten thousand line exchange.

In accordance with one of the objects of my invention I provide a finderswitch sysmm which uses no individual relays to connect the lines with the control equipment but rather uses a single line and cutofi' relay set common to a relatively large group of lines. a

As a further object of my invention I provide a new and improved line equipment of the constantly moving type, to search over the group of lines to which it is common, and to associate calling ones of I said lines with the line relay which is common thereto that relay energizing to control a finder and equipment, to operate that finder into connection with that line.

As a further object of my invention I arrange the constantly moving line equipment so that it acts as an impulse sender, delivering impulses to the motor magnets of a finder switch to step that switch into connection with the calling line. a 1

As a further ob'ect of my invention I use finder switches similar in structure to the Well known rotary line switch whose Wipers have no normal position remaining when not in use on the contacts last used, modified and improved by the inclusion of a marking wiper and associated control apparatus, through which the" position in which the finder is standing is marked in the control equipment, to determine the number of impulses which must be delivered to the finder magnet to position its wipers upon the contacts of the calling line.

Automatic telephone systems of the well known type employ a connector switch which depends upon the finding of a battery potential on the test contact of a called line for the establishment of a connection to that line. That battery potential is supplied to the testing contact through one of the individualrelays associated with that line. Since in the finder system of the present invention there are no individual relays associated with the line, it is necessary to provide a connector arranged to establish a connection with one of these lines.

Further objects of my invention not specifi'cally mentioned here will be apparent from the detailed specification and claims which follow.

The drawings comprising Figs. 1 to 7, inclusive show sutficien't mechanical and electrical details to enable a clear understanding of my invention. Figs. 1 and 2, when arranged with Fig. 2 beneath Fig. 1 with correspondingly numbered lines in alignment, show the usual circuit details of an embodiment of my invention. Figs. 8 and 4 are respectively side and front views of the constantly rotating line equipment switch used in the invention. Figs. 5 and 6 are respectively front and side views of the finder switch mechanism employed in this system, while Fig. 7 is a detailed view of the arrangement of the contacts in the banks of the line equipment switch shown in Figs. 3 and 4.

Referring now to Fig. 1 in more detail, I have shown a subscribers station A, which is ofthe usual type of automatic substation set, comprising a transmitter and receiver in series, an impulse sending device with which thecautomatic switches at the central ofiice are controlled. In Fig. 1 I also show the finder F, connected directly to the first selector E, and having access to the subscribers lines. The selector E is of the well known Strowger type of two-motion switch, whose wipers move in a vertical direction under the control ofthe calling'rdevice at the subscribers station and then rotate automatically under the control of a local testing circuit to pick out the first idle :trunk in the selected group, in this case trunk leading to the connector switch H. Of course it will be understood that by the inclusion of second and third selectors, the total number of lines that can be handled by the system can be increased, but since the selectors form no essential part of this invention, they are not shown, and the selector E shown only in outline form.

The connector H, may be of the well known Strowger type two-motion type switch, whose wipers are moved first in a vertical direction to selecta level of their banks, and then in a horizontal direction to select the desired line in that level, the connector differing from the selector in that both the vertical and rotary motions of the shaft are under the control of the calling device at the subscribers station. The connector H differs from the well known Strowger connector in that the private or testing wiper does not have to find battery in order to switch through and connect with the called line. In the well known Strowger automatic telephone system, an idle line is designated by a high resistance battery potential found on the contacts encountered by the testing wiper, and a busy line is designated by a ground potential upon the same contacts. Inthe switches employed in this system it is necessary that the test wiper of the connector encounters battery potential in order to switch through and connect with the called line. In modifying the standard connector in accordance with the objects of this invention, I have retained the busy uarding feature, that is, provided a circuit such that the connector will not switch through and connect with a called line if the test wiper of the connector encounters ground potential on the test contact of that line. However, I have modified the circuits of the connector so that it is unnecessary for the test wiper to pick up a battery potential in order to switch through and connect with a called line. The reason for this change will be apparent hereinafter. In Fig. 1 I

next set.

have also shown the usual ringing interrupter, generator, and busy tone sources, they being auxiliary equipment essential to the operation of the connectonbut forming no vital part of the present invention.

In Fig. 2 I show the constantly rotating line equipment LE driven by a motor through the gears 313 and 314; I also show a subscribers station B which is identical in every respect with the subscribers station A in Fig. 1. It will be noted that the lines leading from the subscribers stations A and B terminate only in the banks of the finder F and of the line equipment LE, being devoid of the usual individual line and cutoff relay through which the finder switches used heretofore have been controlled. As,

sociated with and individual to the line equipment LE is the relay equipment B, through which the finders are controlled to pick-up a calling line in the manner which will be explained in detail hereinafter. In Fig. 2 I also show the finder allotter FA, which is mechanically similar to the well known rotary line switch, whose wipers move in a forward direction only, and stand when idleupon the contacts last used.

In Figs. 3 and 4 I show the mechanical details of the line equipment LE of Fig. 2, that equipment being somewhat similar to the well known Strowger rotary line switch in that the wipers move in one direction only. The line equipment in this case is mechanically larger than the line switch and is further arranged. so that the wipers are constantly moving over the bank contacts which consist of the bank assembly 311 which comprises five rows of contacts placed in a'semi-circle, there being 25 contacts in each row. Five sets of wipers or brushesare carried on a shaft, one of these brushes encountering each of the contact rows. hebank assembly is supported by the means of support rods 303 and 304C, those rods being so spaced and grooved as to properly line the banks with respect to the main drive shaft. The wiper assemblies are carried .on the main drive shaft 306, which is driven through gears 314i and 315, and which is supported by the main supporting frame comprising301, 302 and 310. Contact with the rotating wipers is obtained by means of a slip ring and brush arrangement, the brushes being designated in Fig. 4 as 307, and 309. One of the slip rings shown is designated as 312. It'should be noted that the slip ring for awiper set, such as the ring 312 for the wiper set 117, is placed at the side so that the brush serving that wiper set lies between it and the That is, the brush engaging ring 312 will lie between wiper sets 117 and 115. In the well known rotary line switch after which this line equipment is patterned, the brush through which connection is made to a wiper set, lies between the members 01? that set. Since the mechanism LE is constantly moving, the line switch brush arrangement Will result in excessive wear, and I have therefore provided the arrangement mentioned above to reduce this wear as much as possible.

F igs. 5 and 6 show respectively the front and side View of the finder switch such as Fof Fig. 1 which I propose to use in an embodiment of theinventien. It will be noted that this finder is quite similar to the afore mentioned rotary line switch and that I have added another wiper 32 and a control magnet 10 which controls the movement of the wiper '32 through the retaining pawl 502. This wiper 32 is mounted upon the same shaft as the main wipers, 36 to 33, inclusive, and is arranged to rotate with them, or to rotate independently. Attached to themain Wiper assembly is he stop 506,-

and attached to the wiper'32 is the stop 509. Lying over on the main shaft 510 is the retaining spring 507 which is wound up when the wipers, 30, 31 211K 33 are advanced and the wiper 82 is held stationary by the retaining pawl 502. Subsequent energization of the magnet 10 attracts its armature withdrawing the pawl 502 from the ratchet wheel 508 of the wiper assembly 32, permitting the springs 50'? to unwind and advance the wiper until the step 509 engages the stop 506 of the main wiper assembly, at which time wiper 32 will come to rest in line with the remaining wipers of the switch. The wipers of the switch have access to a semicircular bank, containing 25 contactsin each row and in this case there are four rows of these contacts. The number of contacts in each row, and the number of rows of contacts of the finder F can be increased or decreased,it beingnecessary only to keep the number of contacts in the row the same the number of contacts in the rows of the banks of the line equipment LE shown in Fig. 3. In Fig. 5, and Fig. 6, the wiper 32 is shown in different positions with re spect to the main wipers 30, 31, 33, the positions being altered to enable a clearer understanding of the structure.

Fig. 7 shows a schematic representation of the bank contacts of the line equipment LE, showing the order in Whichthe wipers 115 to 119 encounter their respective contacts. It will be noted that with the wipers moving in the directionshownby the arrow in Fig. 2, wiper 117 first encounters the contact S belonging to a particularline. Wipers 1l5 and 119 engage the contacts 2and 1 respectively, at the same time, wiper 1 16 engages contact 71 a brief interval later, and wiper 118. engages contact VV. after wipers 115', 117 and 119 have swung free from their respective contacts. Contacts'S, 2, 1, 2" and WV comprise a group ofcontactswhich is individual to one line, there being 2.5 such groups in the line equipment as shown in Figs. 3 and'a.

In'order to simplify the drawings as mu'ch as possible I have shown a plurality of batteries, whereas in an actual installation these would be but one battery, preferably with itspositive pole grounded.

The operation of the system of my invention is briefly as follows: The constantly moving line equipment LE together with the relay group R, takesthe place of the usual individual line and cut-oil relay-s of the well known finder switch systems, and operate jointly to control the positioning of the Wipers of the finders such as F, upon the contacts leading to a calling line such as A. Whena line initiates a call, for example, the receiver is removed from the hook of substation A, that line is in a position topick up a finder and start a call. The removal of the receiver from substation A does nomeeomplish any function until the wipers of the line equipment LE engage the bank contacts associated with that line. When the contacts 115 and 119 of the line equipment engage the contacts 2 and 1 which are associated with the calling line A, a circuit is completed over the loop of the calling line i for the start relay in-the relay equipment R. That relay energizes to prepare circuits for the subsequent control of the finder F. Since the finder F has no normal position, it may happen that its wipers are standing upon the contacts associated with the line A, in'whieh case it will not be necessary to deliver any impulses to the finder F, but only necessary to switchthat finder through and connect the calling'line with the first selector E. After the wipers 115 and 119 havefound a closed loop and energized the start relay, the mark ing wiper 116 has to determine the position of the finder F and if that finder is standing upon the contacts of the line A, a circuit is completed tl'irough the marking wiper 11-6, and the control equipment R switches the finder through without delivering impulses to it. In a majority of instances it will be necessary that the finder be stepped one or more steps to set its wipers upon the contacts of the calling line, in which case no circuit will be completed through the marking wiper 116. As the line equipment LE continues to move, pulse Wiper 118 encounters the contact WV, closing a circuit through the control equipment B and the finder allotter FA to the motor magnet of the finder F,

energizing it preparatory to advancing the finder wipers one step; The energization of the motor magnet of the finder F advances all of the wipers except the marking wiper 32, which is under the control of the individual magnet 10. lVhen the control equipment R is taken into use, all of the wipers except wiper 118 and 11.6 of LE are termporarily cut out of service, since they have no further function in connection with the; setting of the present call. When the equipment rotates so that the wiper 116 engages the next contact in its row, it tests that con tact to determine whether or not the wipers of the finder have been moved a sufficient number of steps to position them upon the contacts of the calling line, and if the wipers: are so positioned a circuit is completed through wiper '116 to switch through the finder and open the pulsing circuit so that no further impulses will be delivered to it. In this manner the finder is advancedunder' the control of wipers 118 and 116 of the.

wiper 110 of the finder allotter FA places:

, arrow.

.ground. potential upon the conductor and the wiper 32 of the finder F. With the .wiper of F in the position shown in Figs.v

1 and 2, if a call is initiated on the line terminating in the contacts of which the wipers 115 and 119 are resting, that line will also appear in the contacts upon which wipers 30 and 33 of the finder F are resting, a circuit may then be traced from this ground on conductor 80 through wiper 32, contact m, conductor a, contact 9, wiper 116, throughsprings 128 which are now closed, through the cut-off relay 106 of the control equipment R, that relay energizingto prepare a switch-through circuit tosprings 130 and to open the impulsing cir-- cuit at springs 132. It a call is initiated by a line one space ahead of where the wipers of the finder F on the line equipment LE are now resting, Wiper 116 which is then engaged with the contact '75, will not find a ground potential and the switchthrough circuit will not be completed. Ac-- cordingly an impulse will be sent to the finder F, to move the wipers 30, 31 and 33 one step in the direction indicated by the Similarly the wipers 115 and 119' of the line equipment LE are moved one step, at which time wiper 116 again engages contact g, and the circuit for relay 106 is completed as before and the finder F is switched through after having taken one step. Magnet 10 of the finder F is then energized, and the wiper 32 is released and moved under the control of spring 507 into alignment with the remaining wipers of the switch. If the line A is the calling line,

with the wipers of the finder Fin the position shown in Fig. 1, it will be necessary to move the wipers two steps to engage the contacts of that line. The circuit for the start relay will be completed when thewiper 115 engages the 2, the wiper 119 engages the contact 1, and the wiper 116 engages the contact 2'. The circuit for relay 106 will he closed, the impulsing circuit will be closed and the'finder will he stepped up one step, at which time the testing wiper 116 will again seek ground. Since two steps are necessary ground potential will .not be present on the contact h, and the pulsing circuit will be again closed to step the wipers one more step at which time contact g is encountered by the wiper 116 and the circuit of relay 106 closed. It will be noted that the wipers of the line equipment LE and the wipers of the finder F move in -opposite directions, that is, the wipers of the finder F move from line 1 to line 25, while the wipers of the line equipment LE move from line 25 to line 1. If the wipers of the finder F were standing on line 1 and line 25 called, it would be necessary to move the wipers of the finder F 24: steps in order to engage the contacts of the calling'line.

Similarly if the wipers of the finder are. standing on the contacts in line 10, and line 15 calls it will be necessary to move the wipers 5 steps in order to bring them in engagement with the contacts of the callin line.

Having thus described my invention in I general I will now proceed with a detailed description of its operation.

Line A calls hen the receiver is removed Vfrom'the hook switch of the station A, a bridge is completed across the line conductors 1 and 2, that bridge including the transmitter, receiver, and impulse springs in series. .The

closure of the direct current bridge across the line conductors is without effect untll the subscribers loop and'the substation toconductor 2, contact 2', wiper 115, conductor 146, through springs 120, through the upper winding of relay 103 to grounded battery. Relay 103 energizes in this circuit and at springs 122 closes a circuit from ground through spring 125 and its break contact, springs 122, thence over two paths in parallel, the one through the upper windmg of relay 105 to grounded battery, and the other through the lower Winding of relay 103, through the lower winding of relay 102, to grounded battery, energizing relays 102 and 105. Relay 103 is-thus maintained energized independent of its initial circuit which is broken by the energization of relay 102 to operate springs 120 and 121. Relay 105 energizes and at spring 127'and its make contact closes a circuit-through conductor 145, through the winding of the motor magnet'lOl of the finder allotter FA, energizing that magnet preparatory to advancing the wipers of the allotter one step. Relay 105 at springs 128 closes a point in the circuit of relay 106, that circuit being held open elsewhere at the moment. Relay 105 at springs 126 closes a high resistance ground through conductor 140 to the. finder F, that circuit being traceable from ground through. resistance 129,,spring 126 and its make contact, conductor 140, wiper 111 of allotter FA, conductor 81, through the winding of relay 11, through resistance 35 to grounded battery. Relay 11 when energized in series with resistances 129 and 35 is capable of closing springs 34, but not sufiiciently strong to operate the remaining springs in its assembly. The closure of springs 34, prepares a testing circuit which will be explained in detail hereinafter. Relay 103 upon energizing, closes at springs 123 a pointin the impulsing circuit preparatory to stepping the wipers of the finder if necessary. The operation'of the system from this point on depends upon whether or not I the wipers of thefinder 'F :happen to be standing upon the contacts of the calling line A at the time.

Finder standing on calling Zine Assume first that the wipers of the finder F are standing on the contacts of the calling line, that is Wiper 30 engaging contact 2", and wiper 33 engaging contact .1" and wiper 32 is engaging the contact 0. In this case it will not be necessary to send any impulses to the'finder, and the circuit will be closed through wiper 110 of the finder allotter FA, conductor 80, wiper 32 of the finder F now engaging contact 0, conductor 0, contact i, wiper 116 which is engaging that contact, conductor 147, through springs 128, through the winding of relay 106 to negative battery. Relay 106 energizes and at springs 132 opens a point in the impulsing circuit to prevent the delivery of any pllges to the motor magnet of the finder. Relay 106 at springs 131 closes parallel circuits for the lower winding of relay 105 to grounded battery, to maintain that relay in its energized position independent of the previously traced circuit through springs 125, and through the lower winding of relay 104 to groundedbattery to energize that relay. Relay 104 upon energizing at spring 125 opens the circuit previously traced for relays 102, 103, and105, and at springs124 and 125 closes a substitute circuit through the upper windingof relay 102 thereby maintaining that relay energized and permitting the relay 103 to deenergize. 103 upon ,deenergizing opens an additional point in the impulsing circuit at springs 123.

The operation ofrelay 106 closes at spring 130 a circuit traceable from ground through that spring, through spring 126 and its make contact, conductor 140, through wiper 111 of the finder allotter'FA, conductor 81 to springs 37, through the winding of magnet 10 of the finder F to grounded battery, with a parallel branch to the winding of relay 11, through resistance 35 to grounded battery. Magnet 10 and relay 11 energize over this circuit, the former to release the wiper 32 to permit it to align itself with the remaining wipers of the switch, but since the finder is assumed to be standing upon the contacts of the calling line, this wiper 32 is already aligned with the remaining wipers of the switch, and the energization of rela therefore performs no useful function. The complete energization of relay 11 connects the calling line to the line relay of the first selector E, that circuit extending from ground through the lower winding of the line relay of E, conductor 39, through springs 39, wiper 33, line conductor 1, through the subscribers loop to line conductor 2, wiper 30, springs 38, conductor 38, through the upper winding of said line relay to grounded battery. The line relay energizes and closesa circuit for the release relay of the selector, that relay energizing to send back ground over the conductor 81 in the wellknown manner, that ground serving to maintain relay 11 in its energizedposition. Relay 11 upon energizing operates springs 36, to close ground through the wiper 31, which is now engaging the private conductor 6 associated with the calling line A, to guard the connection against intrusion by a connector. The calling subscriber isnow connected to the first selector and the usual dial tone is audible to notify him that the equipment is in readiness to receive the impulses: from the calling device to extend the connection to the desired line. Returning now to the equipment-R, the wiper 116 of the line equipment LE continues to revolve and after a brief interval'losesthe ground which is presentupon the contact 2', thereby opening the circuit of relay 106 which falls back after a brief interval. Relay 106 upon falling back opens the circuit of relays 105 and 104, permitting those relays to deenergize, the former to open at springs 127 the circuit of the magnetlOl of the finder alloter FA, that magnet deenergizing to advance the wipers 110 to 113 onto the next contacts in the well known manner.

lay

Finder not standing on contacts of calling line It will most frequently happen that the wipers of the finder F will not be standing on the contacts of the calling line when a call is initiated, and that the control equipment will have to step those wipers one or more steps in order to bring them into engagem'ent with the desired contacts. Assume now that at the time line A is calling, the wipers of F are standing in the position shown in Fig. 1, in which case it will be necessary to move them two steps in order to bring them into engagement with contacts 2 and 1 in which the calling line terminates. Referring now to Fig. 7 it will be noted that shortly after the wipers'115 and 119 engage contacts 2 and 1, respectively, wiper 116 engages the contact I, which contact tests the position of the finder F. Since wiper 32 of the finder F is not standing upon the contact 0, wiper 116 will not complete the circuit for the winding of relay 106, and the pulsing circuit will be left intact preparatory to sending impulses to the magnet of the finder F. When the wiper 118 advances to engagethe contact a circuit may be traced from ground through contact W, wiper 118, conductor 149, springs 123, springs 132, to conductor 142, wiper 113 or" the finder allotter FA, conductor 83 and thence over two paths in parallel, the one through springs 79 through the winding of the motor magnet 7 5 of the'finder F to grounded battery,

energizing that magnet preparatory to advancing the wipers of the switch, the second parallel circuit leads through springs 79, conductor 82, wiper 112 of the finder allotter, conductor 141, through the winding of pulse locking relay 107, to grounded battery, energizing that relay which at springs 133 places a ground on conductor 142 in multiple with that from wiper 118, to lock itself and magnet 7 5 dependent upon springs 79 and 7 9. When the magnet becomes fully energized, springs 79 and 7 9 are operated, opening the circuit of relay 107, and permitting the magnet 7 5 to deenergize, the wiper 118 having passed olt the contact W by this time. Magnet upon deenergizing advances the wipers 30, 31 and 33 of the finder F one step in the direction indicated by'the arrow, the wiper 32 remaining upon the contacts M, being held-there by pawl 502 which'is controlled by the magnet 10. Since two steps are required to bring the wipers F into engagement with the contacts of the calling line, and since the marking wiper 116 of the line equipment LE is now engaging the contact it, having moved to the contact h when the'wiper 118 moved ofi' of contact W, no circuit will be completed for the relay 106, and an additional impulse will be sent to the magnet 75 when the wiper 118 encounters contact W, the circuit being the same as before. When the magnet 7 5 again falls back and advances the Wipers 30, 31 and33 another step, wiper 30 engages contact 2 and wiper 33 engages contact 1 those contacts being the contact of the calling line. 'lViper 32 still being: retained by retaining pawl 502, remains upon contact m and at the end of the impulse when wiper 116 of the line equipment LE moves into engagement with the contact g, acircuit may be traced from ground through wiper 110 of the finder allotter FA, conductor '80, wiper 32 now engaging contact m, conductor a, contact g, Wiper 116, conductor 147 springs 128, through the winding of. relay 106 to grounded battery, energizing that relay which causes the finder to be switched through in the manner hereinbefore explained. The calling subscriber then hears the dial tone, and manipulates his calling device in accordance with the digits of the number of the called station, the first digit operating the first selector E to elevate the wipers 40, 41 and 42, vertically opposite the desired level. The selector E then rotates automatically under control of the testing circuit through Wiper 41, coming .to rest upon the contacts of the first idle trunk line, assumed to be the contacts 43, .44 and 45 of the trunk line leading to the connector H.-

Opemtz'oa 0; the connector H Upon seizure of the connector H, the loop circuit is. closed for the line relay 13 through the contacts 47 and 48 of the back bridge relay 12, through the contacts engaged by Wipers 40 and 41 and thence over the previously traced circuit back through the loop of the calling station. Relay 13 energizes over this circuit and closes a circuit to release relay 14, which energizes to prepare the impulsing circuit at springs 52, supplies ground to holding conductor at springs 51, and applies ground to the release trunk conductor at springs 50, that ground traversing a circuit through contact 44 and wiper 41 to hold, the operated relays of the selector E and the finder F in their operated position. lVhe'n the impulsing. device at the substation A interrupts the circuit of relay 13 in accordance with the next digit oi the call number, line relay 13 falls back and delivers impulses first to the vertical magnet 15 over the circuit including relay 16 in se-v ries, that magnet and relay operating to elevate the shaft and wipers .68 to 70, inclusive, vertically, the latter remaining ene-rgized throughout'the impulsing to perform certain control functions. The first vertical step of the shaft operates the oilnormal spring 55, in the Well known manner, so that when the relay 1 6 falls back at the end of the impulse series, a circuit is extended to the, rotary magnet 22 and the rotary multiple relayi19, to which the next digit dialled into the line relay 13 is delivered. At the end of the second -.digit dialled into the connectorH, the wipers 68, 69, and are positioned upon the contacts of the calling line, assumed to be the contacts 71, 72, and 73, which are connected by the usual multiple cables 1*, 5 and 3", to the lines 3, i, and 5, of the substation B. In order to avoid unnecessary complications of the .drawing this multiple cable is omitted, being indicated by correspondingly nurnbored wires. The operation of the connector H from this point on depends upon whether or not the called'line is busy at the moment.

Assume first that it is busy. Contact 72, associated with the called line, will contain a ground potential if the line is busy. After the wipers have come-to rest on the contact and before the slow acting multiple relay 19 falls back, a circuit may be traced from ground on contact 72, through wiper 6,9, spring and its make Contact, springs 65 through the winding of busy relay 18 to grounded battery, energizing that relay which looks itself to relcasetrunk conductor grounded at spring 50,,through spring 59, thetnormally closed contacts controlled by spring 90, those contacts being closed when the relay 19 restores an instant later, through spring 65 and then through the winding of the relay to grounded battery. The calling subscriber is informed of the busy condition of the line by the busy tone from the busy generator placed on the line through springs 62, in the well known manner. The calling subscriber upon hearing this tone will replace the receiver and release the connection in'the manner which. will be explained in detail hereinafter.

-Assuine however that the calling line is idle at the time the wipers 68 to 70, inclusive, are positioned upon the contacts associated with it. In this case the contact 72 will contain neither battery nor ground'potential, and the connector H will establish the connection to the contacts 71 to 78, inclusive. During theoperation of the rotary magnet 22, to rotate the shaft bearing wipers 68 to 70 intoconnection with the contacts 71 to 73, cam ,93 is operated, upon the first rotary step, closing springs 92 preparatory to switching the connector through if the called line be idle, When the relay 19 falls back after the wiper 69 is positioned on contacts 72 and found that that contact contains no ground potential, a circuit may be traced'from ground through springs 51, off-normal springs 92, springs 60, spring 94, windingof switching relay 20 to grounded battery, energizing that relay which looks itself from ground on spring 51, through springs 65 and then through the winding of the relay to battery. Switching relay 20 upon energizing places ground on contact 72 at springs 6 1 through the wiper 69, that ground marking the line busy to other connectors to prevent intrusion upon the pending call. Relay 20 at springs 63 and 67 connects the wipers 68 and 7 0 to the remainder of the connector, establishing a ringing connection to the'called line. Interrupted ring ing current is projected out over this connection from the generator GEN, under the control of the ringing interrupter ET, the circuit that the ringing current transverses being the usual and well known circuit which is conducting to alternating current and open circuited to the direct current, because of the condenser at the substation B. When the called station B responds to the call by removing the receiver from the hook switch, a direct current bridge is closed across the conductor to the line, energizing the ring cut-off relay 17 which cuts off the ring and switches the connector through as usual. Ring cut-off relay 17 upon energizing operates springs 56 and 58, extending the connection from the called line through to the back bridge relay 12, which furnishes battery to the transmitter of the called station'. Relay 12 energizes and at springs 47 and18 reverses the polarity of the calling line A in the usual manner, placing the two stations in a telephonic connection over which the conversation is carried on.

Release When the stations A and B have complet ed their conversation, and both replace their receivers, ground is removed from the 'release trunk conductor at springs 50 by the deenergization of relay 1 1, and from the connector holding conductor by the deenergization' of back bridge relay 12 and release relay l i at springs 46 and 51, respectively whereupon all relays which were locked to theconductors are released and re stored to normal in the well known manner, placing the equipment 'in its normal position in readiness for the next call. It will be understood of course, that the wipers of the finderF, remain upon the contacts leading to the calling line A, until the finder F is seized again and operated into connection with someother line.

Line equipment rotating over busy line After the finder F has connected with the calling line A and at springs 36 supplied ground to the private conductor 6, and after the connector H has connected with the called lineB and at springs 64 applied ground to the private conductor 5, those lines are protected from intrusion either by a connector or by another finder. The line vate conductor 6 of the calling line A, a

circuit can be traced from ground upon that conductor, through wiper 117, conductor 148, 5hrough normally closed springs 124, through the upper winding of relay 102 to grounded battery, energizing that relay which at springs 120 and 121 disconnects the ground and'start relay circuit from the wipers 119 and 115, respectively. Since the calling line A. is in use at this time a direct current bridge is closed across it, and if the relay 102 were not provided to open the testing circuit, the relay 103 would energize each time the wipers 115 and 119 engage the contacts associated with the line A. This would result in unnecessary operation of the.

finder, and in addition would produce an undesirable click in the receiver of the calling station A. By arranging the wipers of the line equipment LE as shown in Fig. 7, the private wiper 117 first engages the contacts associated with any line. If that wiper picks up a potential ground, relay 102 is energized as just explained, and no further tests are made upon that particular line, the relay 102 remaining energized until the wiper 117 passes off of that particular private contact. It will be noted in Fig. 7 that the private contact S is so shaped that the wiper 117 engages it until after the testing wipers 115 and 119 have freed themselves from the line contacts 2' and 1 so that it is assured that relay 102 will remain energized until after the wipers of the line equipment LE havepassed the line contacts of a busy line.

Oomzeetor calls line A before finder connects with it Since the removal of the receiver from the substation A does not apply ground to the private conductor 6 associated therewith,

and since the conductor 6 is not groundedcable, this cable being omitted from the drawings to avoid any unnecessary complication. When the connector connects with p the line A, ground will be applied to the private conductor 6, and when the wiper 31 of the finder F is positioned on the contact to which this conductor 6 is connected, that ed battery. Relay 11 is so constructed thatthe springs 34 close before the remainder of the springs are moved, that construction being old and well known to those skilled in the art. When the relay 11 is energized in series with resistances 129 and 35, it has suflicient strength to close the springs 34,

however it does not have sufficient strength to fully energize and operate the remainder of its springs. When the wiper' 31 picks up the ground on conductor 6, relay 11 is short circuited from that ground through that wiper, through springs 36 and its break contact, springs 34, throughthe upper terminal of the relay, the lower terminal having been grounded previously from conductor 81. When the relay 106 of the equipment R energizes to switch through the finder, relay 11 is prevented from energizing because of the short circuit, but the equipment R and the finder allotter FA are operated in the usual manner, the former to restore to nor mal and the latter to seek out the next idle finder of the group. When the line equipment LE rotates far enough so that the wlper 117 again engages the contact 6 ground potential will be present on that contact, and the relay 102 will energize to guard that line from intrusion by the control equipment R.

Finder allotter seeks idle finder Returning now to the deenergization of magnet 101 of the finder allotter FA to advance the wipers 110-113 one step in search of the next idle finder. Assume that that step positioned the wipers on the contacts to which conductors -83 are connected and that the finder F is busy at the moment. Conductor 81 will receive a ground potential from the release trunk conductor, as explained above, that ground being picked up by wiper 111 to complete a circuit over which magnet 101 is again energized, that circuit being traceable through wiper 111, conductor 140, spring 126 and its break contact, conductor 143, springs 114, conductor 144, spring 127 and its break contact, conductor 145, through the winding of magnet 101 to grounded battery. Magnet 101 again energizes and opens the above circuit at springs 114, falling back to advance the wipers or" F A one step. If the finder associated therewith is busy, wiper 111 will pick up another ground, and the magnet 101 willoperate in the above buzzer like fashion until that wiper loses ground, at which time the wipers 110-413 will be brought to rest upon the contacts of the idle finder.

From the foregoing description it is apparent that I have designed a new useful finder system which is simple in its construction and which can be easily maintained. In order to avoid unnecessary complications of the drawings, I have shown the system in its simplest form, that is with the calling line multipled only through one finder group and through one line equipment group. In a commercial installation however, I propose to multiple the line conductors to two or more finder groups and to two or more line equipments, thereby increasing the reliability and speed of the system. With the line equipment such as shown in Figs. 3 and l, I am able to rotate the wipers at the speed of about 1 revolution per second, since the wipers are double ending, the lines are tested at the rate of 50 per second. By multiplying each line conductors to two of the line equipments, and by spacing the wipers of the two line equipments degrees apart, each line is tested every quarter of a second instead or every half a second as is the case. when a single line equipment is used. Since the line equipments are being driven by a common motor, it is not difficult to space the wipers in this manner and to maintain that spacing. Each line equipment and its associated control equipment R has access to a different group of finders through the finder allotter such as FA. In this manner the calls are doubly tested, so that in the event one line equipment fails to function properly, due to a mechanical or electrical defect, the other line equipment will pick up the call a quarter of a second later and handle it in the usual manner. In the event or serious trouble in one or the line equipments, the wipers can be thrown out of gear, and repaired at leisure, without in any way interrupting the service. of the line group, since the other line equipment will handle all of the calls occurring therein at that time. Moreover, I have shown the inve tion applied to a twenty five line system, that being aconvenient size and is shown by way of example only, as it is entirely possible to apply the same principles to larger line units or 50 or lines or more.

l Vhile I have chosen to show the invention in connection with the equipment of a par and adaptations which can be made by one skilled in the art without parting from the scope of the invention.

Having thus described my invention, what I consider new and desire to have protected by Iietters'Patent is pointed out in the appended claims.

What is claimed is:

1. In a telephone system, a group of lines, a finder having access thereto, a line relay and a cut off relay common to said lines, means for associating said relays with a calling one of said lines, and means controlled by said line relay responsive to said association for directing said finder to said line to establish a connection therewith.

2. In a telephone system, a group of lines, a finder having access thereto, a line relay and a cut oil relay common to said lines, means for associating said relays with a calling one of said lines, means controlled by said line relay responsive to said asso ciation for directing said finder to said line to establish a connection therewith, and means in said finder for preventing further association of said relays with said line dur ing the progress of said call.

In a telephone system, a group of finder switches, a constantly moving line mechanism, subscribers lines terminating in the banks of said finders and said line mechanism, control equipment through which said line mechanism controls said finders to connect with calling ones of said lines, means in said control equipment responsive to the initiation of a call on one of said lines and operated when said line mechanism is associated with that line for starting a finder, and means in said control equipment for stopping said finder when said calling line is reached to establish a connection thereto.

l. In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, and a switch for connecting said control equipment with a calling one of said lines, said switch then operating to direct a finder to the contacts of that line.

5. In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, a constantly moving switch for associating said control equipment with said lines one at a time and means responsive to the association of said equipment with a calling one or said lines for operating it to direct a finder to the contacts of that line. Y

6. In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control lOO equipment for said finders, a constantly moving switch for associating said control equipment with said lines one at a time, a relay responsive to the association of said equipment with a calling one of said lines, and circuit means completed thereby over which impulses generated by said constantly moving switch are delivered to one of said finder switches to position it upon the contacts of said calling line,

7. In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, a constantly moving switch for associating said control equipment with said lines one at a time, a relay responsive to the association of said equip ment with a calling one or" said lines, circuit means completed thereby over which impulses generated by said constantly moving switch are delivered to one of said finders switches to step it toward the contacts of said calling line, and means controlled jointly by said finder, constantly moving switch and control equipment for determining the number of impulses required to position said finder upon the contacts of said line.

8. In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, a constantly moving switch for associating said control equipment with said lines one at a time, a relay responsive to the association of said equipment with calling one of said lines, circuit means completed thereby over which impulses generated by said constantly moving switch are delivered to one of said finders switches, a relay energized over a circuit completed through said finder vand constantly moving switch when the finder, has received a sufficient number of impulses to position it upon the contacts of said calling line and means controlled by said relay -for preventing the delivering of further impulses to said finder and for causing it to establish a connection with the line.

9. In a telephone system, a subscribers line terminating in the banks of an automatic switch, a second automatic switch operable under the control of the first and having access to said line, means for marking said line idle, busy or calling, means in said first switch for testing said line first for said busy mark then for said calling mark, means operated if said line is calling for testing the position of said second switch, means in said first switch for delivering stepping impulses to said second switch and for determining the number of such impulses required to bring said second switch into connection with said line.

10. In a telephone system, a group of subscribers lines, each of said lines connected only to the bank contacts of several switches, switches having access to said contacts, a relay common to said line group, means for associating said relay with the individual lines of said group in consecutive order, means responsive to the association of said relay with a calling one of said lines and controlled jointly by said relay and said first means to bring a switch into connection with the contacts of that line, and means for then preventing the further association of said relay with said contacts and for preventing any other switch from establishing a connection thereto while said first connection remains established.

11. In a telephone system, a group of sub scribers lines, each of said lines connected only to the bank contacts of switches, said switches having access thereto, a relay group common to said line group, means for associating said relay group with individual lines in consecutive order, one of said relays being energized upon the association of the group with a calling one of said lines to control a means which cooperates with said first means to position one of said switches upon said calling line and to establish a connection thereto, and means for then energizing a second of said relays to prevent the further association of said first relay with said line.

12. In a telephone system, a group of lines, a finder having access thereto, said finder, having no normal position, remains in the position in which it was last set, means for marking that position, means responsive to a call on one of said lines for starting said finder, and means cooperating .with said marking means to determine when said finder has found said line and to stop it to establish a connection therewith.

13. In a telephone system, a finder switch, a line wiper assembly in said switch, a marking wiper assembly in said switch,r means i'or first moving said line wipers independently of said marking wiper and means for thereafter moving said marking wiper independently of said line wipers.

14:. In a telephone system, a finder switch, a line wiper assembly in said switch, a marking wiper assembly in said switch, means for moving said line wipers, means for holding said marking wiper stationary while said line wipers are being moved and means for subsequently releasing said marking wiper.

15. In a telephone system, a finder switch, a line wiper assembly in said switch, a marking wiper assembly in said switch, contact sets to which said wipers have ac cess, said wipers normally standing on their respectivecontacts of one of said sets,

means for moving said line wipers to another set, means ior retaining said marking wiper, means for subsequently releasing said marking wiper and means for moving said released marking wiper to the contact set to which said line wipers have been moved. 7 I

16. In a telephone system, a finder switch, a line wiper assembly in said switch, a marking wiper assembly in said switch, contact sets to which said wipers have access, said wipers normally standing on their respective contacts of one of said sets, means for moving said line wipers to another set, a detent for retaining said marking wiper, means for withdrawing said dctent to release said marking wiper, and means for moving said released wiper to the contact set to which said line wipers have been moved.

17. In a telephone system, a finder switch, a line wiper assembly in said switch, a marking wiper assembly in said switch, contact sets to which said wipers have access, said wipers normally standing on their respective contacts of one of said sets, means for moving said line wipers to another set, a detent for retaining said marking wiper, means for withdrawing said detent to release said marking wiper, and a spring for moving said released wiper to the contact set to which said line wipers have been moved.

18. In a telephone system, a finder switch, a line wiper assembly containing a shaft carrying a plurality of wipers rigidly attached thereto, a marking wiper assembly attached to and free to rotate around said shaft, bank contact sets to which said wipers have access, an aligning member on said line wiper assembly, a stop on said marl:- ing wiper assembly which cooperates with said aligning member to align said assemhlies on one of said contact sets, means for moving said line wipers to another contact set, means for retaining said marking wiper on the contact of said first se means for releasing said retaining means, and means for moving said marking wiper so that said step reengages said aligning member to realign said wiper sets on the latter contact set.

19. In a telephone system, a plurality of calling lines, finder switches having access to said lines, an auxiliary switch for finding a line when calling, said auxiliary switch continuing to operate after connecting with the calling line to cause one of said tinder switches to find said line.

20. In a telephone system, a plurality of lines, an automatic switch having access to said lines, said switch normally standing in the position last used, an auxiliary switch having access to said lines, said auxiliary switch operating to connect with a line when calling, and means for causing both switches to move together after the auxiliary switch connects with the calling line and until the automatic switch connects with the calling line.

21. In atelephone system, a plurality of lines, an automatic switch having access to said lines, an auxiliary switch havingaccess to said lines and operating to connect with a line when calling, means for causing said switches to move together after the auxiliary switch connects with the calling line, and means for stopping the automatic switch. when it connects with the calling line.

22. In a telephone system, a plurality of lines, an aiiitomatic switch having access thereto, said switch normally standing in the position last used, an auxiliary switch having access to said lines and operating to connect with a line when calling, means for moving said switches together after said auxiliary switch connects with the calling line, and means for stopping said automatic switch when it connects with the calling line, the extent of novement of said automatic switch determined by said auxiliary switch.

23. In a telephone system, a plurality of lines, an automatic switch having access thereto, said switch normally standing in the position lastused, an auxiliary switch having access to said lines for finding a line when calling, said auxiliary switch continuing to operate after connecting with the calling line, and means or moving said automatic switch under the control of said auxiliary switch until said automatic switch is connected with the calling line.

2a. In a telephone system, a plurality of lines, an automatic switch having access thereto, said switch normally standing in the position in which it was last set, means in said switch for marking that normal position, an auxiliary switch having access to said lines and operating to connect with a line when calling, and means for moving the automatic switch with the auxiliary switch after the auxiliary switch connects with the calling line, said auxiliary switch cooperating with said marking means to determine the amount of movement necessary for the automatic switch to reach and to stop that switch when line.

25. In a telephone system, a group of lines, a line relay and a cut-off relay common to said group, and means for periodically associating said relays with each line of the group, said line relay operating responsive each association if the line is originating a call, said cut-oil relay operating responsive to each association if the line is busy to prevent the operation of said line relay.

26. In a telephone system, a group of lines, a line relay common to said group, means for periodically associating said line relay w th each line of the group, said relayoperatmg it reaches that the calling line 7 responsive to the association with calling ones of said lines to operated responsive to the association of said relay with extended calling lines to prevent the operation of said relay.

27. In a telephone system, a group of lines, means for marking said lines calling or busy, a line relay and a cut-off relay common to said lines, and means for periodically associating said relays with each line of the group, said line relay operating *esponsive to the association with a line marked calling, said cut-off relay operating responsive to the association of a line marked busy.

28. In a telephone system, a group of lines, means for marking said lines calling or busy, a line relay and a cut-off relay common to said lines, and means for periodically associating said relays with each of said lines, said line relay operating responsive to the association with a line marked calling, said cut-0d relay operating responsive to the association with a line marked busy to prevent the operation of the line relay,

and neither of said relays operating responsive to the association with a line lacking said markings.

29. In a telephone system, a group of lines, a finder having access thereto, said finder normally remaining in the position last used, and means responsive to a call on one of said lines for directively operating said finder from its last used position to connect with said calling line.

30. In a telephone system, a line, an automatic switch having access to said line and other lines, said switch normally remaining in the position last used, and means for directively operating said switch from its last used position into engagement with said line.

31. In a telephone system, a group of lines, an automatic switch having access to said lines and normally remaining in the position last used, an impulse sender, and means in said sender responsive to a call on one of said lines for transmitting only the required number of impulses necessary to step said-switch from its last used position to its new position in engagement with the said calling line.

32. In a telephone system, a line, an automatic switch having access to said line and normally remainin' in the position last used, and a sender for transmitting a variable number of impulses to directively operate said switch into engagement with said line, the number of impulses transmitted to said switch in any given setting being dependent upon the last used position of said switch. 7

33. In a telephone system, a line, an automatic switch having access to said line and other lines, said switch normally remaining in the position last used, a register in said extend them, and means 7 switch for marking said last used posi ion, an impulse sender, means for operating said sender to generate impulses, and means con trolled by said register for determining the numb-e of impulses to be transmitted by said sender to said switch to operate said switch from its last used position into on gagement with said line.

34. In a telephone system, a group of lines, an automatic switch having access to said lines,a sender also having access to said lines, a register in said switch, means for operating said sender into engagement with successive ones of said lines, means in said sender responsive to the sender encountering a calling one of said lines for transmitting impulses to directively operate the switch, and means controlled by said register for stopping the transmission of impulses when the switch encounters the calling line. 7

In a telephone system, a group of lines connected only to contacts of switch banks, directively controlled finder switches hav ing access to certain ones of said contacts, a control equipment, a'switch having access to certain others of said contacts for associating said control equipment with said lines one at a time, and a third switch irdividual to said switch and control equipment for preselecting an idle one of said finders and for connecting such. finder to said control equipment.

36.11 1 a telephone system, a gri'iup o1 lines, an automatic switch having access to said lines in a certain order, an impiilse sender having access to said lines in reverse order to said certain order, a register normally remaining in the position last used, means for operatingsaid sender into successive engagement with said lines in said reverse order, and means in said sender responsive to the sender engaging a calling one of said lines for transmitting a vari able number of impulses to directively operate said switch into engagement with said calling line, the number of impulses sent to said switch being dependent upon the num ber of succenlve lines in the sender bank intervening between the calling line and the position marked by the register.

37. In a telephone system, a group of lines, a line relay and a cut-ofi' relay common to said group, means for periodically associating said relays with each line of the group, said line relay operating responsive to each association if the line is originating a call, said cut-off relay operating responsive to each association if the line is busy to prevent the operation of said line relay, and means controlled by the operation of said line relay for closing a locking circuit for itself including saio cut-oil relay.

88. In a telephone system, a group of lines,

a line relay common to said group, means for periodically associating said line relay with each line in said group, said line relay operating responsive to each association if this line is originating a call, and means controlled by the operation of said line relay for closing a locking circuit for itself.

39. In a telephone system, a group of lines, a line relay common to said group, means for periodically associating said relay with each line in said group, said line relay operating responsive to each association if the line is originating a call, a finder switch having access to said lines and normally remaining in the position last used, and means jointly controlled by said operated line relay and said periodic associating means for directively operating said finder to the calling line.

40. In a telephone system, a group of lines, a line relay and a. cut-off relay common to said group, means for periodically associating said relays with each line of the group, said line relay operating responsive to each association if the line is originating a call, said cut-off relay operating responsive to each association if the line is busy to prevent the operation of said line relay, a finder switch having access to said lines, and means jointly controlled by the operated line relay and said periodic associating means for directively operating said finder to the calling line.

41. In a telephone system, an automatic switch, line wipers and a marking wiper in said switch, said line and marking wipers normally remaining in the position last used, means for moving the said line wipers independently of said marking wiper, and means for thereafter moving the said marking wiper.

42. In a telephone system, an automatic switch, line wipers and a marking wiper in said switch, said line and marking wipers normally remaining in theposition last used, means for moving said line wipers to a new position, said marking wiper remaining in its last used position during such movement, and means for thereafter moving said marking wiper in alignment with said line wipers in its new position.

43. In an automatic switch having no-normal position and having wipers adapted to engage contacts in any position, means for retaining one of said wipers in the position last used until the other of said wipers have been completely set in a new position, and means for thereafter releasing said one wiper to said new position.

4:4:- In a telephone system, a subscribers line terminating in the banks of an automatic switch, a second automatic switch operable under the control of the first and having access to said line and no normal position, means for marking said line idle, busy or calling, means in the first switch for testing said line first for said busy mark then for said calling mark, means operated if said line is calling for testing the position of said second switch, means in said first switch for operating the said second switch to bring said second switch into connection with said line.

4-5, In a telephone system, a group of telephone lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, a switch having access to certain others of said contacts for associating said control equipment with said lines one at a time, means in said switch for generating impulses during its operation, a relay responsive to the association of said equipment with a calling one of said lines, circuit means completed by said relay over which impulses generated by the switch are delivered to one of said finders, a second relay energized over a circuit completed through said finder and switch when the finder has received a suflicient number of impulses to position it upon the contacts of said calling line, and means controlled by said second relay for preventing the delivering of further impulses to said finder 46. In a telephone system, a group of lines connected only to the contacts of switch banks, finder switches having access to certain of said contacts, control equipment for said finders, a switch having access to certain other of said contacts, means for operating said switch to connect said control equipment with a calling one of said lines, and means controlled by the operation of said switch after connecting the control equipment with the calling line for directively operating one of said finders to the contacts of the calling line.

47. In a telephone system, the combination of a finder switch, a group of lines, and a sender switch, line and test contacts of successive ones of said lines terminating in the finder bank in a certain order, multiple connections of said contacts also terminating in contacts in the sender bank in a reverse order to said certain order, controlling contacts of the finder bank multipled with controlling contacts of the sender bank, and wipers cooperating with said contacts for controlling the transmission of impulses to said finder switch and for completing a connection to one of said lines.

48. In a telephone system, a group of lines, finders having access to said lines, a common switch having access to said lines, means for operating said common switch, means in said common switch responsive to the association of said common switch with a calling one of said lines for thereafter directively operating one of said finders to establish a connection with said calling line, and means responsive to such association for seizing said common switch for the exclusive use of the calling line until said finder has completed the connection to the calling line.

49. In a telephone system, a line equipment, subscribers lines terminating in bank contacts in said line equipment, a finder switch normally remaining in the position lastused and having a directively controlled motion for connecting with a calling line, testing wipers in said line equipment, means for operating said wipers, and means responsive to the association of said wipers with the bank contacts of a calling one of said lines for thereafter directively operating said finder from its last used position to connect with the said calling line.

50. In a telephone system, a line equipment, subscribers lines terminating in bank contacts in said line equipment, a finder switch having a dir'ectively controlled mo tion for connectingwith a calling line, a pulsing wiperin said line equipment, testing wipers in said line equipment, means for operating said wipers, and means responsive to the association of said wipers with the bank contacts of a calling one of said lines for thereafter directlvely operating said finder under control of said pulsing wiper to establish a connection with the calling line.

51. In. an impulse sender for directively operating an automatic switch to complete a connection, a pulsing wiper, testing wipers, a counting wiper, means for operating said wipers, means controlled over said test ipers for rendering said pulsing wiper effective to transmit impulses to said switch, and means controlled over said counting wiper for rendering said pulsing wiper ineffective to transmit further impulses.

52. In a telephone system, subscribers lines terminating in switch bank contacts, a finder switch, wipers in said finder having access to said lines by way of said -con tacts, the wipers of said finder normally remaining in the position last used in the contacts of a suhscribers line, means responsive to a call on one of said lines for directively operating the wipers of said finder from its last used position to the contacts of the calling line to extend a connection, and means for extending the connection without directively operating said finder in case the wipers of the finder are in engagement with the contacts of said calling line at the time such line initiates a call.

In witness whereof, I hereunto subscribe my name this 1st day of July, A. D. 1926.

RUDOLPH F. STEHLIK. 

